Application of passive power filter with induction motor soft starter

The paper addresses the issues of electromagnetic compatibility of the thyristor voltage regulator (TVR) applied for induction motor soft start with the power network. In particular, it shows an impact of soft starters implemented on the basis of the TVR on the network voltage wave shape at their connection points. Under certain conditions, a distortion level of the regulator can exceed a maximum limit. In such cases, passive power filters (PPF) may be used to improve a voltage harmonic composition. It is shown that the PPF application improves induction motor start-up conditions; this fact should be taken into account in the PPF design. The methodology of filter parameters calculation is proposed in the paper. The simulation results are also presented, showing a significant reduction of the higher harmonics level and the motor start-up time when the passive power filter is used. It is concluded that the PPF installation in the thyristor soft starter systems of induction motors is advisable.